PROJECT SUMMARY/ABSTRACT Significant progress has been made in the functional neuroimaging of stuttering, but the complex interactions between brain, behavior, and environment that support stuttering remain incompletely understood. This gap in knowledge is due in part to the context in which neural activity has been observed. It is well known that stuttering occurs primarily in the context of social interaction?people tend not to stutter when speaking alone, or to babies and pets. Yet, in almost all cases, functional neuroimaging studies have focused on non-social and non- communicative speech. These studies point to atypical neural function within the speech and sensorimotor networks, but social-cognitive networks have not been directly investigated in this population. The long-term goal of this Early Career Research proposal is to develop a line of programmatic research that expands the study of stuttering from sensorimotor control into the social-cognitive domain. This proposal focuses on adults, with the goal of extending the approach to children in future studies. The overall objectives in this application are to determine the neural impact of two social-cognitive factors with particular relevance to stuttering?social interaction and anticipation?and determine the relationship(s) between these neural data and behavioral outcomes. The central hypothesis is that social-cognitive processing de-stabilizes the speech motor systems of adults who stutter. The rationale for this study is that determining the impact of social-cognitive processing on stuttering will contribute to the development of a strong theoretical framework that narrows the brain-behavior- environment gap and ultimately informs new directions in stuttering intervention. The central hypothesis will be tested by pursuing two specific aims. Aim 1 evaluates the neural impact of social interaction in adults who stutter (AWS) and those who do not by manipulating social context (i.e., the presence or absence of a communicative partner). Aim 2 determines the neural correlates of anticipation, which is rooted in prior social experiences, by comparing neural activation associated with ?feared? and ?non-feared? words (i.e., words expected and not expected to be stuttered, respectively), in AWS. Feared and non-feared words are determined during a novel clinical interview developed by the research team. This application is innovative in that it uses functional near- infrared spectroscopy (fNIRS) which permits the measurement of neural signals during face-to-face speech communication, thereby increasing ecological validity in the neuroimaging of stuttering. The proposed research is significant because by expanding the study of stuttering into the social-cognitive domain, we will be able to address critical questions about how brain, behavior, and environment contribute to stuttering. In addition, focusing on social interaction and anticipation has specific treatment implications. For example, identifying the neural correlates of stuttering during social interaction can be used to guide neuromodulation approaches such as transcranial direct current stimulation that are now beginning to be applied to stuttering.